Lamb production and feed intake in relation to degradability characteristics and metabolisable protein content of dried subterranean clover diets

A study was undertaken of three cultivars of subterranean clover (cvv. Larisa, Trikkala and Goulburn), harvested at 50% flower and again after 30 days, for liveweight gain and wool growth of lambs. Live weight gain (LWG) and wool growth (WG) of lambs were significantly higher (P<0.001) at 50% flower than from the later harvest. The LWG and WG of lambs fed three cultivars of subterranean clover ranged from 137 to 162 and 8.9 to 12.7 g day−1, respectively at 50% flower while at the later harvest, they ranged from 97 to 106 and 7.1 to 7.8 g day−1, respectively. No significant differences in the live weight gain were observed between cultivars. The higher wool growth of lambs fed cv. Trikkala at 50% flower compared with lambs fed cv. Goulburn or cv. Larisa was associated with significantly higher intake of metabolisable protein, but no difference in wool growth and metabolisable protein were observed between lambs fed cv. Goulburn and cv. Larisa diets. The relations of feed intake with degradability characteristics of dry matter and cell wall organic matter (CWOM) were investigated. The inclusion of rate of degradation of CWOM with CWOM content per se significantly improved the predictive relationship for organic matter intake (R2=0.55) and digestible organic matter intake (R2=0.65). This study has quantified strong predictive relations of live weight gain and wool growth with the intake of metabolisable protein (R2=0.66) for subterranean clover.